Great question. Per the rules (below) Windows Mobile apps (running on a smarthphone or tablet) are eligible.
4.B.(iii) Platforms: An Application must run on at least one of the following mobile platforms:
a smartphone or tablet (iOS, Android, Blackberry, Windows Mobile, or Kindle)
a mobile web browser
other mobile hardware (including, but not limited to, wearable technology, open source hardware, or proprietary hardware)